It has been long known to provide a self-ejecting chuck key in order to insure that the key will be withdrawn from operating position on the chuck and thereby insure against its being inadvertently left in position upon starting of the machine. A number of designs have been offered for this purpose for upwards of fifty years and many are currently available on the market. However, for one reason or another, the previously known designs have not been fully satisfactory and it is the purpose of the present invention to provide such a chuck key which will be inexpensive and yet fully effective and reliable.
More particularly, certain keys of the prior art have utilized internal spring-loaded plungers which are coaxial with the gear on the key and bear against the chuck body. Such keys are held in position manually by the operator and when the manual force holding same in position is released, such spring-loaded plunger responds to the urging of a spring, pushes against the chuck body and ejects the key from its operating position. These keys are effective but they are expensive to manufacture and if the hole inside of the key which contains the plunger becomes loaded with dirt and/or metal particles the self-ejecting mechanism may become inoperative.
Another related form of such key provides for a plunger to lie in a longitudinal groove on a surface of the key and same is urged by a spring into an outwardly extended position. This plunger likewise bears against the chuck body and pushes the key out of operating position when the manual force thereon is removed. This is somewhat less expensive to make than the abovementioned type but it is still subject to being rendered inoperative if the plunger carrying slot becomes excessively loaded with dirt and/or particles of metal. Further, since the ejecting force of this key is eccentric to the gear and pilot for same, there is some tendency for the key to tilt in response to the urging of said spring-loaded plunger and, at least in some positions, certain such keys now on the market tend to bind in the pilot opening and/or on the bevel gear and fail to release.
Still other types of such keys utilize an external coaxial chuck body surrounding the key but functioning in the same manner as the above-mentioned plungers. This operates effectively in some instances but is not well adapted to use with a gear chuck inasmuch as the external chuck body will be prevented by the gear teeth from contacting other than the jaw nut of the chuck which again means that the force tending to retract the key from its operating position will be eccentric to the center of the key and cause same to tilt and occasionally bind in its operating position.
The foregoing three basic forms are expressed in a variety of particular ways in the prior art, but all of them insofar as I am aware involve one or more of the various problems mentioned above.
Accordingly, the objects and purposes of the invention include the following:
1. To provide a self-ejecting key for a gear chuck which will be inexpensive to manufacture but fully reliable under all normal conditions of operation. PA1 2. To provide a self-ejecting key, as aforesaid, having no closely fitting or closely machined parts which can be rendered inoperative by accumulation of dirt and/or metal particles but will on the contrary be sufficiently free and open that such accumulation will not inhibit its operation. PA1 3. To provide a self-ejecting chuck key, as aforesaid, wherein the ejecting force will be arranged at least substantially uniformly around and in alignment with the axis of the key whereby to minimize the likelihood of its being pushed angularly and thereby jamming in place. PA1 4. To provide a self-ejecting chuck key, as aforesaid, wherein the mechanism for effecting the self-ejecting will be fully visible at all times and is such that if anything should occur which would inhibit its proper functioning, same can be readily seen and either corrected or the key replaced. PA1 5. To provide a self-ejecting chuck key, as aforesaid, which will utilize for most of the final product a presently standard key, together with a single relatively inexpensive added part whereby same can be rapidly and inexpensively assembled from presently standard keys without special machining being done thereon and hence at a minimum of cost.
Other objects and purposes of the invention will be apparent to persons acquainted with apparatus of this type upon reading the following specification and inspection of the accompanying drawing.